According to the present prior art, the dominant influence of variation of the water content in the working fluid of a gas turbine installation and its effect on the operating characteristics of the individual gas turbine components have been investigated adequately and are sufficiently well known. This knowledge is of practical relevance in particular for closed-loop control of the combustion temperature of a gas turbine of a modern type, in order to make it possible to comply with the very stringent requirements for highly loaded components in these gas turbines, in terms of a life and emissions.
Closed-loop control of the combustion temperature of a gas turbine as a function of the water content of a working medium of the gas turbine is described in EP 1 231 369 A2. In this known closed-loop control, the water content of the air flowing into the gas-turbine compressor is determined and is used as a further parameter for determining the combustion temperature. One or more sensors is or are used to determine the water content and, in particular, is or are also placed downstream from water injection in the machine.